U.S. patent application number 10/792279 was filed with the patent office on 2005-01-13 for haptic devices having multiple operational modes including at least one resonant mode.
Invention is credited to Cruz-Hernandez, Juan Manuel, Grant, Danny, Hayward, Vincent.
Application Number | 20050007342 10/792279 |
Document ID | / |
Family ID | 34961337 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050007342 |
Kind Code |
A1 |
Cruz-Hernandez, Juan Manuel ;
et al. |
January 13, 2005 |
Haptic devices having multiple operational modes including at least
one resonant mode
Abstract
An apparatus comprises a signal source, a driver and an
electro-mechanical transducer. The signal source is configured to
output a haptic feedback signal. The driver is configured to
receive the haptic feedback signal and output a drive signal. The
electro-mechanical transducer is configured to receive the drive
signal. The electro-mechanical transducer is configured to have a
set of operational modes. Each operational mode from the set of
operational modes has at least one resonant mode from a set of
resonant modes.
Inventors: |
Cruz-Hernandez, Juan Manuel;
(Montreal, CA) ; Grant, Danny; (Montreal, CA)
; Hayward, Vincent; (Montreal, CA) |
Correspondence
Address: |
COOLEY GODWARD LLP
ATTN: PATENT GROUP
11951 FREEDOM DRIVE, SUITE 1700
ONE FREEDOM SQUARE- RESTON TOWN CENTER
RESTON
VA
20190-5061
US
|
Family ID: |
34961337 |
Appl. No.: |
10/792279 |
Filed: |
March 4, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10792279 |
Mar 4, 2004 |
|
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10301809 |
Nov 22, 2002 |
|
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60375930 |
Apr 25, 2002 |
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Current U.S.
Class: |
345/161 |
Current CPC
Class: |
B06B 1/0603 20130101;
H01L 41/094 20130101; G06F 3/016 20130101 |
Class at
Publication: |
345/161 |
International
Class: |
G09G 005/08 |
Claims
What is claimed is:
1. An apparatus, comprising: a first electro-mechanical device, the
first electro-mechanical device having a first end portion and a
second end portion, the first end portion of the first
electro-mechanical device being fixedly coupled to a base member,
the first electro-mechanical device being configured to operate in
a plurality of resonant modes; a second electro-mechanical device,
the second electro-mechanical device having a first end portion and
a second end portion, the first end portion of the second
electro-mechanical device being fixedly coupled to a base member,
the second electro-mechanical device being configured to operate in
a plurality of resonant modes; a first mass coupled to the second
end portion of the first electro-mechanical device; and a second
mass coupled to the second end portion of the second
electro-mechanical device, the first electro-mechanical device and
the second electro-mechanical device being configured collectively
to operate in a plurality of operational modes, each operational
mode from the plurality of operational modes being uniquely
associated with at least one of a resonant mode from the plurality
of modes for the first electro-mechanical device and a resonant
mode from the plurality of modes for the second electro-mechanical
device.
2. The apparatus of claim 1, wherein the first mass is different
than the second mass.
3. The apparatus of claim 1, wherein the first electro-mechanical
device has a length, the second electro-mechanical device having a
length different than the length the first electro-mechanical
device.
4. The apparatus of claim 1, further comprising: a third
electro-mechanical device, the third electro-mechanical device
having a first end portion and a second end portion, the first end
portion of the third electro-mechanical device being fixedly
coupled to a base member; and a third mass coupled to the second
end portion of the third electro-mechanical device, the first
electro-mechanical device, the second electro-mechanical device and
the third electro-mechanical device being configured collectively
to operate in a plurality of operational modes.
5. The apparatus of claim 1, wherein the first electro-mechanical
device is a piezoelectric device.
6. The apparatus of claim 1, wherein the first electro-mechanical
device is a piezoelectric device and the second electro-mechanical
device is a piezoelectric device.
7. The apparatus of claim 1, wherein the first electro-mechanical
device is one of a resonant eccentric rotating mass, and an
electro-active polymer device.
8. The apparatus of claim 1, further comprising: a voltage source,
the voltage source being configured to apply a voltage to the first
electro-mechanical device and the second electro-mechanical device
in response to a signal.
9. A method, comprising: receiving a drive signal associated with a
haptic feedback signal; and applying the drive signal to an
electro-mechanical transducer, the electro-mechanical transducer
operating in at least one resonant mode from a plurality of
resonant modes in response to the drive signal.
10. The method of claim 9, the electro-mechanical transducer being
a first electro-mechanical device, the method further comprising:
applying the drive signal to a second electro-mechanical device
different from the first electro-mechanical device, the first
electro-mechanical device and the second electro-mechanical device
collectively operating in one operational mode from a plurality of
operational modes in response to the drive signal for the first
electro-mechanical device and the drive signal for the second
electro-mechanical device.
11. The method of claim 9, the electro-mechanical transducer being
a first electro-mechanical device, the method further comprising:
applying the drive signal to a second electro-mechanical device
different from the first electro-mechanical device, the first
electro-mechanical device and the second electro-mechanical device
collectively operating in one operational mode from a plurality of
operational modes in response to the drive signal for the first
electro-mechanical device and the drive signal for the second
electro-mechanical device, the plurality of operational modes
including a first operational mode and a second operational mode;
and changing from the first operational mode to the second
operational mode, at least one the resonant mode of first
electro-mechanical device and the resonant mode of the second
electro-mechanical device for the first operational mode differing
for the second operational mode.
12. The method of claim 9, the electro-mechanical transducer being
a first electro-mechanical device, further comprising: applying the
drive signal to a second electro-mechanical device different from
the first electro-mechanical device, the first electro-mechanical
device and the second electro-mechanical device collectively
operating in one operational mode from a plurality of operational
modes in response to the drive signal for the first
electro-mechanical device and the drive signal for the second
electro-mechanical device, the first operational mode being
associated with the applying the drive signal to the first
electro-mechanical device when the drive signal to the second
electro-mechanical device is not applied, the second operational
mode being associated with the applying the drive signal to the
second electro-mechanical device when the drive signal to the first
electro-mechanical device is not applied.
13. A method, comprising: receiving a drive signal; and applying
the drive signal to an electro-mechanical transducer, the
electro-mechanical transducer having a plurality of operational
modes in response to the drive signal, each operational mode from
the plurality of operational modes having its own combination of at
least one resonant mode from a plurality of resonant modes.
14. The method of claim 13, the electro-mechanical transducer being
a first electro-mechanical device, the plurality of operational
modes including a first operational mode and a second operational
mode, the drive signal being associated with the first operational
mode, the method further comprising: applying the drive signal to a
second electro-mechanical device different from the first
electro-mechanical device, the second electro-mechanical device and
the first electro-mechanical device collectively having the
plurality of operational modes.
15. The method of claim 13, the electro-mechanical transducer being
a first electro-mechanical device, the method further comprising:
applying the drive signal to a second electro-mechanical device
different from the first electro-mechanical device, the second
electro-mechanical device and the first electro-mechanical device
collectively having the plurality of operational modes, the
plurality of operational modes including a first operational mode
and a second operational mode; and changing from the first
operational mode to the second operational mode by altering a
characteristic of the drive signal.
16. The method of claim 13, the plurality of operational modes
including a first operational mode and a second operational mode,
the drive signal being associated with the first operational mode,
the method further comprising: changing from the first operational
mode to the second operational mode by altering a characteristic of
the drive signal.
17. An apparatus, comprising: a signal source, the signal source
being configured to output a haptic feedback signal; a driver, the
driver being configured to receive the haptic feedback signal and
output a drive signal; and an electro-mechanical transducer being
configured to receive the drive signal, the electro-mechanical
transducer being configured to have a plurality of operational
modes, each operational mode from the plurality of operational
modes having at least one resonant mode from a plurality of
resonant modes.
18. The apparatus of claim 17, wherein the electro-mechanical
transducer is a piezoelectric transducer.
19. The apparatus of claim 17, wherein the electro-mechanical
transducer is an electro-active polymer.
20. The apparatus of claim 17, the electro-mechanical transducer
being a first electro-mechanical device, the apparatus further
comprising: a second electro-mechanical device different from the
first electro-mechanical device, the second electro-mechanical
device being configured to receive the drive signal, the plurality
of operational modes being associated with the first
electro-mechanical transducer and the second electro-mechanical
transducer collectively.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application is a continuation-in-part and claims
priority to U.S. patent application Ser. No. 10/301,809, entitled
"Haptic Feedback Using Rotary Harmonic Moving Mass" and filed Nov.
22, 2002; and U.S. Patent Application No. 60/375,930, entitled
"Haptic Feedback Using Rotary Harmonic Moving Mass" and filed Apr.
25, 2002; the disclosure of both being incorporated by
reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to the application of
vibrotactile feedback. More particularly, the invention relates to
a haptic feedback device having multiple operational modes
including multiple resonant modes.
BACKGROUND OF THE INVENTION
[0003] Generally, electro-mechanical transducers exhibit a level of
power consumption that may be higher than desired. Furthermore,
such electro-mechanical transducers may not be able to produce
haptic feedback of a desired magnitude or bandwidth due to space
constraints.
[0004] What is needed is an electro-mechanical transducer that is
configured to produce vibrotactile feedback having a relatively
high magnitude and/or an adjustable bandwidth. Additionally, it
would be desirable to have an electro-mechanical transducer that
can generate haptic feedback having relatively low energy
consumption.
SUMMARY OF THE INVENTION
[0005] An apparatus comprises a signal source, a driver and an
electro-mechanical transducer. The signal source is configured to
output a haptic feedback signal. The driver is configured to
receive the haptic feedback signal and output a drive signal. The
electro-mechanical transducer is configured to receive the drive
signal. The electro-mechanical transducer is configured to have a
set of operational modes. Each operational mode from the set of
operational modes has at least one resonant mode from a set of
resonant modes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a system block diagram of an electro-mechanical
transducer, according to an embodiment of the invention.
[0007] FIG. 2 shows a perspective view of an electro-mechanical
device according to an embodiment of the invention.
[0008] FIG. 3 shows a perspective view of an electro-mechanical
transducer according to an embodiment of the invention.
[0009] FIG. 4 shows a perspective view of an electro-mechanical
transducer according to another embodiment of the invention.
[0010] FIG. 5 shows a perspective view of an electro-mechanical
transducer in a parallel arrangement, according to an embodiment of
the invention.
[0011] FIG. 6 illustrates a plot of a gain profile for a single
resonant mode output from single electro-mechanical transducer
according to one embodiment of the invention.
[0012] FIG. 7 illustrates a plot of a gain profile for multiple
resonant modes output by an electro-mechanical transducer according
to an embodiment of the invention.
[0013] FIG. 8 shows a perspective view of an electro-mechanical
transducer in a series arrangement according to another embodiment
of the invention.
[0014] FIG. 9 shows a side view of an electro-mechanical transducer
shown in FIG. 8 in a rest position.
[0015] FIG. 10 illustrates the electro-mechanical transducer
according to the embodiment depicted in FIG. 8 operating in a first
resonant mode.
[0016] FIG. 11 illustrates the electro-mechanical transducer
according to the embodiment depicted in FIG. 8 operating in a
second resonant mode.
[0017] FIG. 12 illustrates the electro-mechanical transducer
according to the embodiment depicted in FIG. 8 operating in a third
resonant mode.
[0018] FIG. 13 is a flow chart illustrating a method for producing
an operational mode of an electro-mechanical transducer according
to an embodiment of the invention.
DETAILED DESCRIPTION
[0019] An apparatus comprises a signal source, a driver and an
electro-mechanical transducer having a cantilever. The signal
source is configured to output a haptic feedback signal. The driver
is configured to receive the haptic feedback signal and output a
drive signal. The electro-mechanical transducer has a cantilever
and is configured to receive the drive signal. The
electro-mechanical transducer is configured to have a set of
operational modes. Each operational mode from the set of
operational modes has at least one resonant mode from a set of
resonant modes.
[0020] In one embodiment, electro-mechanical devices are used in an
electro-mechanical transducer that is configured to output haptic
feedback in an operational mode having one or more resonant modes.
The electro-mechanical transducer is also configured to have
multiple operational modes. Such a device can produce diverse and
robust haptic feedback that can exhibit relatively low power
consumption in a space-efficient manner. Although many embodiments
described herein relate to using cantilevers as resonant
structures, analogous devices are also possible. For example, such
resonant structures can use acoustic cavities, membranes,
mass-springs, wheel-torsional springs, and/or other structures
capable of exhibiting mechanical resonance. Some embodiment, for
example, can have a combination of different types of structure
capable of exhibiting mechanical resonance.
[0021] As used herein, the term "operational mode" means a method
or manner of functioning in a particular condition at a given time.
For example, if a first electro-mechanical device is operating in a
first resonant mode and a second electro-mechanical device is
operating in a second resonant mode, the electro-mechanical
transducer is operating collectively in, for example, a first
operational mode. Alternatively, for example, if the first
electro-mechanical device is operating in a third resonant mode,
and the second electro-mechanical device is operating in a fourth
resonant mode, the electro-mechanical transducer is operating
collectively in a second operational mode. In another example, if
the first electro-mechanical device is operating in a first
resonant mode, and the second electro-mechanical device is not
operating, the electro-mechanical transducer is operating
collectively in a third operational mode. In other words, a given
operation mode can be based on one electro-mechanical device
operating in a resonant mode and another electro-mechanical device
not being activated.
[0022] The term "resonant mode" means any mode of an
electro-mechanical device operating in a frequency band centered
around a resonant frequency. When an electro-mechanical device
operates at or near a resonant frequency, several consequences
occur. For example, when a transducer operates at or near a
resonant frequency, the inertial term and the elastic terms
substantially cancel. The power consumed by the actuator is then
dedicated to balance dissipation (e.g. damping). If the dissipation
is low, for example, in a cantilevered piezo-electric beam (i.e. a
resonator with a high Q factor), the displacement is relatively
large and limited by dissipative forces. In addition, if the mass
that resonates is comparable to the mass of the structure to which
the transducer is attached (e.g. case of a telephone), then the
structure vibrates with a relatively large magnitude. Power lost
during activation is in the dissipation. The remaining power is
transmitted to the anatomy of the person with which the device is
in contact.
[0023] The term "electro-mechanical device" as used herein, means
an individual active component configured to provide haptic
feedback. The term "active component" refers to a single component
that provides a mechanical response to the application of an
electrical signal. For example, for the embodiment illustrated in
FIG. 5 and discussed below, a single length of, for example,
piezoelectric material (for example, piezoelectric bar 410) and the
associated mass (for example, mass 412) is referred to herein as
the electro-mechanical device. In the example illustrated in FIG. 8
and discussed below, the electro-mechanical transducer includes
only one electro-mechanical device.
[0024] The term "electro-mechanical transducer" means an apparatus
having one or more electro-mechanical devices coupled to a
mechanical ground. For example, in the embodiment of the invention
illustrated in FIG. 5, the electro-mechanical transducer includes
all three lengths of piezoelectric material, each having a mass
coupled thereto. In the embodiment illustrated in FIG. 8, the
electro-mechanical transducer includes piezoelectric bar 610 and
the masses 620, 630, and 640.
[0025] An embodiment of an electro-mechanical transducer is
illustrated in FIG. 1. An electro-mechanical transducer according
to this embodiment of the invention includes a drive circuit 110
having an amplifier and includes an electro-mechanical transducer
120. The electro-mechanical transducer 120 includes one or more
electro-mechanical (E-M) devices 121.
[0026] Drive 110 receives a haptic feedback signal and outputs a
drive signal to electro-mechanical transducer 120. The haptic
feedback signal may be based on a command from a microprocessor
within, for example, a computer or a portable communications device
(not shown). The electro-mechanical transducer 120 is configured to
selectively operate in one of multiple possible operational modes
at a given time. The operational mode of the electro-mechanical
transducer 120 at a given time will depend, for example, on the
characteristics of the drive signal received from driver 10. For a
given operational mode, an electro-mechanical transducer can
operate in multiple resonant modes as will be described in greater
detail below. The one or more electro-mechanical devices 121 of
electro-mechanical transducer 120 collectively output haptic
feedback based on the drive signal, as illustrated in FIG. 7.
[0027] FIG. 2 illustrates a piezoelectric bar in accordance with
one embodiment of the invention. As described below in more detail,
such a piezoelectric bar can be used as an electromechanical device
within an electro-mechanical transducer.
[0028] The piezoelectric bar 200 is a bimorph piezoelectric device
that is a two-layer bending motor having a length (L) 220
substantially larger than a width (W) 210. In one embodiment, the
piezoelectric bar 200 has a width (W) 210 of approximately 0.6 mm,
a length (L) 220 of approximately 25 mm and a height (H) 230 of
approximately 5 mm. Alternatively, the piezoelectric bar can have
any suitable dimensions depending on the desired use.
[0029] When a voltage 240 from, for example, a drive source (not
shown), is applied across the piezoelectric bar 200, the
piezoelectric bar 200 will flex. An appropriate level of voltage
240 to be applied to the piezoelectric bar 200 can be selected,
based at least in part, on the material and the thickness of the
material used to construct the piezoelectric bar 200.
[0030] The piezoelectric bar 200 can be driven near a resonant
frequency. When the piezoelectric bar 200 is driven near a resonant
frequency, impedance transformation may be obtained. Impedance
transformation results in large mechanical displacements as
described above.
[0031] An electro-mechanical device 300 that can be used in
combination with other electro-mechanical devices to construct an
electro-mechanical transducer is illustrated as FIG. 3. Multiple
electro-mechanical devices 300 can be configured to operate in a
selected operational mode from a set of possible operational modes,
each operational mode having one or more resonant modes, as will be
described in further detail with respect to FIG. 5.
[0032] The electro-mechanical device 300 illustrated in FIG. 3
includes a piezoelectric bar 310 having mass 320 coupled to an end
portion 325 of the piezoelectric bar 310. A second end portion 335
of the piezoelectric bar 310 is coupled to a base member 330. Base
member 330 acts as a mechanical ground and is configured to remain
stationary relative to the movement of the piezoelectric bar
310.
[0033] The electro-mechanical device illustrated in FIG. 3 can
operate as follows. A voltage 340 from a voltage source (not shown)
can be applied to piezoelectric bar 310. The piezoelectric bar can
be, for example, a bimorph piezoelectric device as described above
in connection with FIG. 2. Voltage 340 causes piezoelectric bar 310
to flex in a first direction D.sub.1. Voltage 340 can be modulated
at a frequency, f.sub.d, which is referred to herein as the drive
frequency of the electro-mechanical device 300. As described above,
the frequency f.sub.d can be selected such that the
electro-mechanical device 300 operates near a resonant frequency
the electro-mechanical device 300. Frequency f.sub.d is a function
of the type of electro-mechanical device used in the
electro-mechanical transducer, the dimensions of the
electro-mechanical device (e.g., the length, width, height or
thickness), and the position and weight of the masses in the
electro-mechanical device.
[0034] When the drive frequency f.sub.d of the voltage 340 is such
that the electro-mechanical device 300 operates near its resonant
frequency, the electro-mechanical device 300 can produce a large
vibration sensation relative to the voltage 340 applied to the
electro-mechanical device 300.
[0035] Both the weight of mass 320 and the length of the
piezoelectric bar 310 affect the amplitude of the displacement.
Furthermore, the weight of mass 320 and the length of the
piezoelectric bar 310 affect the resonant frequencies of the
electro-mechanical device 300. Therefore, the particular resonant
frequencies may be tailored by selecting the appropriate length of
the piezoelectric bar and/or weight of the mass 320 for a desired
resonant frequency. When voltage 340 is applied to the
piezoelectric bar 310, the electro-mechanical device 300 will move
in a plane oriented as vertical for the depiction in FIG. 3.
[0036] The embodiment illustrated in FIG. 4 is similar to that
illustrated in FIG. 3. FIG. 4 shows an electro-mechanical device
350 including a piezoelectric bar 360 having mass 370 coupled to an
end portion 375 of piezoelectric bar 360. The piezoelectric bar 360
has its second end portion 385 coupled to a base member 380, which
acts as a ground and is configured to remain stationary with
respect to movement of the piezoelectric bar 360.
[0037] The operation of the electro-mechanical device 350 is
similar to the embodiment described with reference to FIG. 3 except
that when voltage 390 is applied to piezoelectric bar 360, the
electro-mechanical device 350 will vibrate in direction D.sub.2
(i.e., relative to the perspective shown in FIG. 4) due to the
orientation of the bimorph piezoelectric bar 360 relative to base
member 380.
[0038] FIG. 5 illustrates an electro-mechanical transducer 400,
according to another embodiment of the invention. The
electro-mechanical transducer 400 includes three electro-mechanical
devices 410, 420, and 430. In the illustrated embodiment, each of
the electro-mechanical devices 410, 420 and 430 includes a
piezoelectric bar 411, 421, and 431, respectively. A mass 412, 422,
and 432 can be coupled to an end portion 413, 423, or 433, of each
piezoelectric bar 411, 421 and 431, respectively. The second end
portion 414, 424, and 434, of each piezoelectric bar 411, 421, and
431, respectively, is coupled to a base member 440. Base member 440
can be configured to remain stationary with respect to movement of
the piezoelectric bars 411, 421 and 431. More specifically, base
member 440 is stationary relative to any movement of piezoelectric
bars 411, 421 and 431, but can move in the context of the overall
product or device (e.g., mobile phone, game controller, etc.) with
which the electro-mechanical device 400 is disposed. In fact, base
member 440 can relay the vibrations produced by the movement of
piezoelectric bars 411, 421 and 431 to the product or device. Base
member 440 may be a single contiguous mechanical ground, as
illustrated in FIG. 5. Alternatively, each piezoelectric bar 411,
421, and 431 may be coupled to a different mechanical ground.
[0039] Piezoelectric bars 411, 421, and 431 have lengths L1, L2,
and L3, respectively. In one embodiment, these lengths may be the
same. Alternatively, lengths L1, L2, and L3 can be different.
Additionally, the weights of masses 412, 422, and 432, can be equal
to one another. Alternatively, weights of the masses 412, 422, and
432 can be different from one another. The particular configuration
of the masses 412, 422 and 432 and the lengths of the piezoelectric
bars 411, 421, and 431 can be based on the desired frequency
response from the electro-mechanical transducer 400.
[0040] The operation of the electro-mechanical transducer in FIG. 5
will be described with reference to FIGS. 4 and 5. Voltage 450 can
be applied to the electro-mechanical devices through contacts 451.
The voltage may by modulated at approximately the resonant
frequency of the electro-mechanical devices 410, 420, and/or 430.
The voltage may be applied by a single voltage source via contacts
451, or alternatively, each electro-mechanical device 410, 420,
430, may have an independent voltage source (not shown) that is
modulated approximately at the resonant frequency of the respective
electro-mechanical device, or a resonant mode of the respective
electro-mechanical device. Alternatively, voltage 450 may be
modulated at a higher order resonant frequency of the
electro-mechanical devices 410, 420, and/or 430.
[0041] In an alternative arrangement, the electro-mechanical
transducer 400 can include electro-mechanical devices 410, 420, and
430 that have different lengths L1, L2, L3. In this arrangement,
each of the electro-mechanical devices 410, 420, and 430 has a
different resonant frequency f.sub.1, f.sub.2, and f.sub.3,
respectively. These different resonant frequencies can be driven at
different drive frequencies f.sub.d1, f.sub.d2, and f.sub.d3. An
example of the frequency response for an electro-mechanical
transducer 400 is illustrated in FIG. 7. As depicted in the plot in
FIG. 7, an electro-mechanical transducer with three
electro-mechanical devices each operating at a different resonant
frequency (or resonants thereof) has a frequency response with a
greater bandwidth than the frequency response for an
electro-mechanical transducer having a single electro-mechanical
device, which is illustrated in FIG. 7. Note that the gain values
shown on the y-axes in FIGS. 6 and 7 relate to the magnitude of the
device position divided by the magnitude of the input voltage to
the device.
[0042] In another arrangement, masses 412, 422, and 432 and lengths
L1, L2, and L3 of electro-mechanical devices 411, 421, and 431 can
be configured such that a single drive frequency, f.sub.d, may be
used to drive, for example, the resonant mode in electro-mechanical
device 411, the first resonant mode in electro-mechanical device
422, and the second resonant mode in electro-mechanical device
432.
[0043] In yet another arrangement, the bandwidth of the
electro-mechanical transducer 400 may be adjusted by selectively
operating one or more of the electro-mechanical devices 410, 420,
430 in different resonant modes. Each one of these combinations of
resonant frequencies collectively superpose into a different
operational mode of the electro-mechanical transducer 400.
[0044] In a first operational mode, for example, the
electro-mechanical transducer 400 can be operated such that
electro-mechanical devices 410 and 430 may be operating at
frequencies f, and f.sub.3, respectively, with f.sub.1 and f.sub.3
being resonant modes of the electro-mechanical devices 410 and 430,
respectively. A voltage need not be applied to electro-mechanical
device 420 in this operational mode. In this operational mode, the
output of the electro-mechanical transducer 400 would include peaks
510 and 530 illustrated in FIG. 7.
[0045] In a second operational mode, for example, the
electro-mechanical transducer 400 can be operated such that
electro-mechanical devices 410 and 420 are operating at frequencies
f.sub.1 and f.sub.2, respectively, where f.sub.1 and f.sub.2 are
resonant modes of the electro-mechanical devices 410 and 420. In
this operational mode, the electro-mechanical transducer 400 can
produce an output having only two peaks, as illustrated, for
example, in FIG. 7 as 510 and 520. This operational mode can have
two frequencies that are different from the two frequencies of the
first operational mode described above. Therefore, by changing the
operational mode of the electro-mechanical transducer 400, the
resultant frequencies of the tactile feedback can be changed.
[0046] In a third operational mode, for example, the
electro-mechanical transducer 400 can be operated such that
electro-mechanical devices 420 and 430 may be operating at
frequencies f.sub.2 and f.sub.3, respectively, where f.sub.2 and
f.sub.3 are resonant modes of each of the electro-mechanical
devices 420 and 430. In this operational mode, the
electro-mechanical transducer 400 can produce an output having only
two peaks, as illustrated, for example, in FIG. 7 as 520 and 530.
This operational mode can have two frequencies that are different
from the two frequencies for first operational mode described
above. Additionally, the third operational mode can have two
frequencies that are different from the two frequencies of the
second operational mode. Therefore, by changing the operational
mode of the electro-mechanical transducer 400, the resultant
frequencies of the haptic feedback can be changed.
[0047] In other operational modes, the electro-mechanical
transducer 400 can be operated such that one of electro-mechanical
devices 410, 420 and 430 is operating at frequencies f.sub.1,
f.sub.2 and f.sub.3, respectively, where f.sub.1, f.sub.2 and
f.sub.3 are resonant modes of each of the electro-mechanical
devices 410, 420 and 430. In these operational modes, the
electro-mechanical transducer 400 can produce an output having only
one peak at a time. In other words, operational modes are possible
where only a single electro-mechanical device is actuated at a
given time.
[0048] The voltage can be modulated at a number of different drive
frequencies, f.sub.d. For example, the drive frequency f.sub.d can
approximate a resonant mode of the electro-mechanical devices.
Alternatively, f.sub.d can include any other frequency that is an
integral multiple of the electro-mechanical device's resonant
frequency.
[0049] While certain operational modes have been described with
reference to FIG. 5, it will be apparent from this discussion that
many other operational modes are possible. For example, by
providing additional electro-mechanical devices, the number of
possible operational modes increases. Additionally, while only
three piezoelectric bars were illustrated in FIG. 5, any number of
piezoelectric bars may be employed.
[0050] Additionally, while the embodiments were described above
with reference to electro-mechanical devices that included
piezoelectric bars, any electro-active material or device can be
used. For example, the electro-mechanical devices can include
electro-active polymers (EAP), voice coil transducers or other
electromagnetic device, an inertial resonant device, or a resonant
eccentric rotating mass (HERM) device. An example of an inertial
resonant device is described in co-pending U.S. Pat. No. 6,088,019,
which is hereby incorporated by reference in its entirety. An
example of a HERM device is described in co-pending patent
application Ser. No. 10/301,809, which is hereby incorporated by
reference in its entirety.
[0051] FIG. 8 illustrates an alternative embodiment of an
electro-mechanical transducer 600 having multiple masses 620, 630,
and 640 disposed on the same piezoelectric bar 610.
[0052] In this embodiment, electro-mechanical transducer 600
comprises one electro-mechanical device, the structure of which
corresponds to the structure of electro-mechanical transducer 600.
The piezoelectric bar 610 is secured to a base member 650, which
acts as a mechanical ground and remains substantially fixed with
respect to the movement of the electro-mechanical device 600.
Masses 620, 630, and 640 can have equal weights or can have
different weights. Alternatively, the weights of the two masses can
be equal to one another, while the weight of the third mass can be
different. Additionally, the masses 620, 630, and 640 can be
equally spaced along the length of the piezoelectric bar 610 or can
be spaced at any desired location along the length of the
piezoelectric bar 610. The weight of and spacing between masses
620, 630, and 640 allow the electro-mechanical device to be
designed to have a predetermined number of resonant
frequencies.
[0053] Next, the operation of the embodiment illustrated in FIG. 8
will be described with reference to FIGS. 6-10. FIGS. 7-10
illustrate an example of the different operational modes that can
be obtained with an electro-mechanical transducer 600 bearing three
masses. The bends in the piezoelectric bar 610 are exaggerated in
this figure to illustrate the bending of the piezoelectric bar 610
more clearly.
[0054] Frequency modulated voltage can be applied to the
piezoelectric bar 610. As illustrated in FIG. 9, the
electro-mechanical device is initially in a resting position. FIG.
10 illustrates a first resonant mode of the electro-mechanical
device. FIG. 11 illustrates a second resonant mode of the
electro-mechanical device. FIG. 12 illustrates a third resonant
mode of the electro-mechanical device. The modes illustrated in
FIGS. 7-10 will produce a resultant output having frequencies that
are similar to the frequencies illustrated in FIG. 7 due to the
superposition of the three resonant modes produced by the
electro-mechanical device.
[0055] FIG. 13 illustrates a method for producing an operational
mode of an electro-mechanical transducer, according to an
embodiment of the invention. At step 1110, a haptic feedback signal
is generated. At step 1120, the haptic feedback signal is supplied
to a driver. At step 1130, the drive signal is then applied to a
first electro-mechanical device. At step 1140, a drive signal is
also applied to the second electro-mechanical device. At step 1150,
the electro-mechanical devices output haptic feedback that includes
haptic feedback at a first resonant mode (step 1151) and haptic
feedback at a second resonant mode (step 1152). The output of
haptic feedback at a first resonant mode by a first
electro-mechanical device and/or at a second resonant mode by a
second electro-mechanical device correspond to an operational mode
of the electro-mechanical transducer having the first
electro-mechanical device and/or the second electro-mechanical
device, respectively.
[0056] Additional electro-mechanical devices can be added and can
have the drive signal selectively applied thereto to collectively
yield a variety of different operational modes of the
electro-mechanical transducer. Alternatively, the
electro-mechanical transducer may include multiple masses, as
illustrated in FIG. 8. By altering the frequency of the drive
signal such that it substantially corresponds to the resonant
frequencies of the electro-mechanical device, the
electro-mechanical transducer can output haptic feedback having
multiple frequencies for a given operational mode.
[0057] In another embodiment, a number of electro-mechanical
devices in a serial configuration, as illustrated in FIG. 8, can be
arranged in parallel as illustrated in FIG. 5.
[0058] The devices described above are capable of being used in
small, portable devices where energy consumption needs to be low.
For example, electro-mechanical transducers can be used in cellular
phones, electronic pagers, laptop touch pads, a cordless mouse or
other computer peripherals whether cordless or otherwise, a
personal digital assistant (PDA), along with a variety of other
portable and non-portable devices.
[0059] While the particular embodiments of the invention were
described above with respect to piezoelectric bars, the invention
is not limited to the use of piezoelectric bars and piezoelectric
devices having various structures can be used depending on the
desired application of the electro-mechanical transducer. For
example, the piezoelectric device can have a planar shape where the
width is approximately the same as the length.
[0060] While particular embodiments of the invention have been
described with reference to piezoelectric ceramics, numerous other
electro-mechanical devices may be used to implement the invention.
For example, the electro-mechanical devices according to the
invention may include electro-active polymers (EAP), voice coil
transducers or other electromagnetic device, or resonant eccentric
rotating mass (HERM) devices.
[0061] While various embodiments of the invention have been
described above, it should be understood that they have been
presented by way of example only, and not limitation. Thus, the
breadth and scope of the invention should not be limited by any of
the above-described embodiments, but should be defined only in
accordance with the following claims and their equivalence.
[0062] The previous description of the embodiments is provided to
enable any person skilled in the art to make or use the invention.
While various electro-mechanical transducers have been described
including at least one electro-mechanical device including a
piezoelectric substance, various other electro-mechanical devices
may be utilized that can be configured to operate in multiple
operational modes, each one of the multiple operational modes
including a number of resonant modes. Other modifications to the
overall structure of the electro-mechanical devices and arrangement
of the selector-mechanical transducers can be made without
departing from the spirit and scope of the invention.
* * * * *